ReadableStream initial implementation

Source/core/streams/UnderlyingSource.h

Index: Source/core/streams/UnderlyingSource.h
diff --git a/Source/core/streams/UnderlyingSource.h b/Source/core/streams/UnderlyingSource.h
new file mode 100644
index 0000000000000000000000000000000000000000..2a7c4936b043aa351d3f7bbd2e3d08da54c82056
--- /dev/null
+++ b/Source/core/streams/UnderlyingSource.h
@@ -0,0 +1,24 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UnderlyingSource_h
+#define UnderlyingSource_h
+
+#include "platform/heap/Heap.h"
+
+namespace WebCore {
+
+class UnderlyingSource : public GarbageCollectedFinalized<UnderlyingSource> {
+public:
+    virtual ~UnderlyingSource() { }
+    virtual ScriptPromise startStream(ExceptionState*) = 0;
+    virtual void pullStream(ExceptionState*) = 0;
+    virtual void cancelStream(ExceptionState*) = 0;

[tyoshino (SeeGerritForStatus), 2014/07/18 04:31:40]

are these suffixes needed? it looks like Stream is the object of the preceding
verb but it's not. they are invoked by the corresponding stream.

[yhirano, 2014/07/18 04:38:54]

Yes, they are called by ReadableStream objects. But they can be implemented in a
fat class such as XMLHttpRequest, I think. In such a case cancel is too simple.

[tyoshino (SeeGerritForStatus), 2014/07/18 04:49:54]

Oh, I see. How about did prefix? Hmm, still too simple?
- didStreamStart
- didStreamPull
- didStreamCancel

- streamDidStart
- streamDidPull
- streamDidCancel

or

- readableStreamDidStart
- readableStreamDidPull
- readableStreamDidCancel

are the safest, but maybe just stream is fine for now.

[yhirano, 2014/07/18 06:33:37]

How about suffixing Source?

[tyoshino (SeeGerritForStatus), 2014/07/18 07:14:47]

Sounds good

+    virtual void trace(Visitor*) { }
+};
+
+} // namespace WebCore
+
+#endif // #ifndef ReadableStream_h
+